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Backing Bearings

The Sankai Ganghai Co., Ltd. NNCF series of backing bearings of was originally developed for cold rolling mills of the cluster types in the 1980s. Backing bearings are roller bearings having a particularly thick-walled outer ring that can be mounted on stationary support shafts to form back-up or straightening rolls. (Picture 1 is of the backing bearings on the eight support shafts of a 20-roll mill). The NNCF series of backing bearings are produced in many designs but generally based on double or three-row cylindrical roller bearings, in the form of full complements bearings ( without cage) or as caged bearings, with or without integral flanges or flange rings, also with contact or non-contact seals. Single row roller bearings and double row tapered roller bearing designs are also available. Because lubricant is supplied to the bearings via the support shaft, the bearings have lubrication holes and some have one or more annular grooves in the inner ring.

 

The advantage of the bearings without flanges lies in their particularly    simple geometrical form and their very high radial load carrying capacity. Cylindrical roller backing bearings without flanges or flange rings cannot accommodate any axial load. It is therefore necessary to place thrust washers of bronze or plastic between the side faces of the outer ring and the support saddles.

 

Thrust washers are not required using backing bearings with flanges (or flange rings) as the design of these bearings enables them to accommodate simultaneously acting radial and axial forces.

 

The NNCF series of backing bearings can also be designed and manufactured to meet customers’ special needs. The structures of the NNCF series of backing bearings in Sankai Ganghai Co., Ltd. are shown as follows:

 

 

Tolerance and Materials

The NNCF series of backing bearings lead to more accurate rotation than GBP4 bearings. In particular, control of cross-sectional difference is more stringent and generally less than 5 um in the same group, the difference between neighboring  frames is less than 3um.

Fitting Instructions

Before the NNCF series of backing bearings leave the factory, they are strictly labeled according to the requirements of the customers. Support shafts with the same interface are assembled on a shaft and installed based on serial numbers. The stability and flexibility of bearing rotation is examined after assembly.

Lubrication

The majority of multi-roll mills and support bearings are lubricated by oil or grease.  The viscosity of emulsions used for bearing lubrication should be at least 8-12mm at 40 Celsius, and the flow rate must be higher than that of normal lubricating oil. The degree of cleanliness also has a decisive impact on the service life of support bearings, requires multiple-level filtering. The lubrication of sealed bearings or double row tapered roller bearings must use oil mist or point of lubrication oil. The viscosity of the lubrication oil must be between 100 and 150mm at 40 degree Celsius.

Maintenance and Re-processing

It is inevitable that foreign body rolled or uneven wear, will lead to damages to the outer cylindrical surface. Types of damage include: indentation, flattened areas and irregularities caused by cold welding. In order to avoid the premature failure of the support, the external diameter must be re-ground.

 

After grinding, the outer ring must be cleaned and re-measured, fit with an appropriate roller and re-assembled with the inner frame to form completed support bearings. The height of cross-sections will also be re-measured before assembly.

We offer maintenance and reprocessing services to fit your need. Or we can provide introduction to bearing grinding, work fixtures and cross section height diameter as needed.

 

Application

The NNCF series of backing bearings are widely used in 20 high roller, 14 high roller, 12 high roller, 8 high roller and offset 8-high cold plate mills. They can also used in roll straighteners and press brakes. In fact they have become the most preferred products of many multi-roll cold mills factories cities such as Beijing, Tianjin, Zhengzhou, Shanghai and Guangzhou, in part because we have speeds of

10M/S, and rolled sheets as thin as 0.005mm. Sankai Ganghai Bearing Manufacture Co., Ltd was the first, and now the largest domestic manufacturer of high quality backing bearings. Our productions accounts of more than 80% of domestic productions. Dozens of our standard bearing products widely used by industries and municipalities and are universally praised by customers..